'The Sign of Three' is not only the most divisive and, on first watch, confusing episodes of Sherlock, but it's also one of the most ambitious. More importantly though, it's a lesson that you should never judge an episode until it's finished. The mysteries all tie themselves together at the end, but for much of this episode, it's like a sitcom, as Sherlock and John get drunk, dance to Rihanna and make serviettes. The speech from Sherlock is genuinely moving; he feels both more human in this episode, and totally detached from society, but it's the final third, when Irene Adler appears, Mycroft shouts at him in his mind palace, and he has to solve a case quickly - and stop being a "drama queen" - that this episode really excels. 'The Sign of Three', like 'The Empty Hearse', is more about the characters that Moffat and co have built, rather than the plot. Mary ascends to someone we can all love, the John/Sherlock relationship develops into an unstoppable bond and we see further into the character of Sherlock than ever before. Why should that be divisive?
